Unexpectedly impressive performances by Guardians of the Galaxy and a reboot about half-shelled ninjas have only partially lightened the gloom that is this year’s monster-movie season.

Photo: Reuters

Hollywood unleashed a noisy barrage of monsters, mutants and superheroes this summer, blowing up the world several times, but the roster of blockbusters did not quite provoke the reaction expected: America yawned.

Studios spent hundreds of millions making and promoting individual movies for the expected seasonal rush to multiplexes, only for their films to run out of steam within days and be rechristened “summer bummers.”

Domestic summer box-office revenue fell approximately 15 percent, one of the biggest year-on-year declines in decades and the final tally may come in below $4 billion for the first time in eight years.

Big-budget offerings including Godzilla, The Amazing Spider-Man 2, X-Men: Days of Future Past and Transformers: Age of Extinction did not exactly bomb. Opening weekends brought in ticket sales of US$90 million to US$100 million. But then, like King Kong tumbling from the Empire State Building, they crashed to earth.

In their second weekend Spider-Man fell 59 percent, Godzilla 67 percent, and X-Men and Transformers 64 percent. Now, with Labor Day approaching, headlines like “Summer bummer” and “Summer of slump” are capturing Tinseltown’s bleak mood.

“What other product spends millions in preparing for launch — and in six weeks it’s gone?” asked Arthur de Vany, author of Hollywood Economics: How Extreme Uncertainty Shapes the Film Industry.

“You put all this money up front and all you really have is a can of celluloid. You don’t really know what’s going to happen.”

Unexpectedly impressive performances by Guardians of the Galaxy and Teenage Mutant Ninja Turtles in August, traditionally summer’s slowest month, have only partially lightened the gloom. Exceptional circumstances, such as the World Cup and the absence of a Pixar film, did not help.

Not for the first time, studio executives are struggling to fathom the industry’s mysterious economics. Last summer there were spectacular flops such as The Lone Ranger and RIPD, failures that entered Hollywood lore, but at the same time there were record box-office receipts of US$4.75 billion thanks to hits such as Despicable Me 2 and Iron Man 3. The purple patch lasted into the first half of this year, raising hopes of a bumper summer, and there have been critical and commercial successes: Disney’s Maleficent, a reworking of Sleeping Beauty starring Angelina Jolie; 20th Century Fox’s Dawn of the Planet of the Apes, a sequel to the 2011 reboot; Marvel’s Guardians of the Galaxy, which launches a new franchise; and the Turtles, which tapped nostalgia for the original TV series and movies.

But the steep drop-offs after opening weekend are a big concern. The producer Robert Evans famously compared a movie’s opening to a parachute jump: “If it doesn’t open, you are dead.”

Still true, but opening strongly is not enough if hardly anyone subsequently turns up. Godzilla, which roared to US$93 million domestic box-office opening, three months later hovers at US$200 million, according to Box Office Mojo. Transformers, the only film to exceed a US$100 million domestic opening this summer, has topped out at around US$243 million, the lowest in the four-film franchise.

The original Star Wars fell just 15 percent week on week and lasted in theatres for months. Now you would be lucky (or unlucky, depending on taste) to find the giant lizard or alien robots on a big screen in the US.